Wireless communication using radio frequencies has become increasingly widespread in the last decade and many communication systems now compete for a limited resource. As a result, one of the most important parameters for wireless communication systems is how efficiently they can use the allocated frequency spectrum.
The requirement for an efficient use of the scarce frequency spectrum resource has led to the development of wireless technologies that can operate with high levels of interference. For example, it is a key requirement for high capacity cellular communication systems that a high level of interference can be permitted. Typically these communication systems operate with a frequency reuse of one, which means that the same channel bandwidth is available and is used in all sectors and cells across the network. As a result, the intercell interference seen from the neighbor cells can be very substantial at the cell overlap areas. Since the power available to the transmitter is constrained, the available Carrier to Interference Ratio (C/I) and hence the data rate is also constrained under this condition. If the intercell interference can be removed, the effective C/I increases and the data rate increases commensurate with the improvement in C/I. This may provide a much higher spectral efficiency and increase the capacity of the system substantially, and it is therefore highly desirable to remove or mitigate the intercell interference.
A communication scheme which may be used in wireless communication systems is the Orthogonal Frequency Division Multiple (OFDM) scheme. Furthermore, a cellular communication system may use Orthogonal Frequency Division Multiple Access (OFDMA) wherein users in the same cell are assigned sub-carrier groups that are simultaneously active with other user's sub-carrier groups. However, in OFDMA, transmissions within a cell may be kept orthogonal and the interference generated to users in the same cell (intracell interference) can be effectively mitigated to the extent that it can typically be ignored.
However, interference from other cells (intercell interference) is not orthogonal and may consequently appear as interference and degrade the transmissions. As a consequence, it is highly desirable to mitigate the impact of the intercell interference. Techniques for mitigating intercell interference are well known in the art and an example of a method of intercell interference mitigation can be found in A. E. Jones and S. H. Wong; “Generalised Multiuser Detection in TD-CDMA”, Proceedings of IEEE Vehicular Technology Conference, Stockholm, May 2005, the Institute of Electrical and Electronic Engineers, incorporated by reference herein.
However, a problem with the known approaches for mitigation of interference is that the performance and efficiency is highly dependent on information relating to the interferers. This information is typically difficult to obtain for the individual receiver resulting in the relatively inaccurate estimates or assumptions being used. As a consequence, the interference mitigation is frequently suboptimal and results in a significant degradation of the communication quality and a reduction of the capacity of the cellular communication system.
Hence, improved interference mitigation for OFDM communication would be advantageous and in particular a system allowing increased flexibility, improved performance, increased system capacity, facilitated operation, reduced complexity and/or improved provision of information enabling, facilitating or improving interference mitigation would be advantageous.